2W3X

Crystal structure of a bifunctional hotdog fold thioesterase in enediyne biosynthesis, CalE7

2W3X の概要

• エントリーDOI: 10.2210/pdb2w3x/pdb
• 分子名称: CALE7, PHOSPHATE ION, O-(O-(2-AMINOPROPYL)-O'-(2-METHOXYETHYL)POLYPROPYLENE GLYCOL 500), ... (6 entities in total)
• 機能のキーワード: hydrolase, hotdog fold, thioesterase, enediyne biosynthesis
• 由来する生物種: MICROMONOSPORA ECHINOSPORA
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 104252.69

構造登録者

Kotaka, M.,Kong, R.,Qureshi, I.,Ho, Q.S.,Sun, H.,Liew, C.W.,Goh, L.P.,Cheung, P.,Mu, Y.,Lescar, J.,Liang, Z.X. (登録日: 2008-11-17, 公開日: 2009-04-07, 最終更新日: 2023-12-13)

主引用文献

Kotaka, M.,Kong, R.,Qureshi, I.,Ho, Q.S.,Sun, H.,Liew, C.W.,Goh, L.P.,Cheung, P.,Mu, Y.,Lescar, J.,Liang, Z.X.
Structure and Catalytic Mechanism of the Thioesterase Cale7 in Enediyne Biosynthesis.
J.Biol.Chem., 284:15739-, 2009

PubMed Abstract: The biosynthesis of the enediyne moiety of the antitumor natural product calicheamicin involves an iterative polyketide synthase (CalE8) and other ancillary enzymes. In the proposed mechanism for the early stage of 10-membered enediyne biosynthesis, CalE8 produces a carbonyl-conjugated polyene with the assistance of a putative thioesterase (CalE7). We have determined the x-ray crystal structure of CalE7 and found that the subunit adopts a hotdog fold with an elongated and kinked substrate-binding channel embedded between two subunits. The 1.75-A crystal structure revealed that CalE7 does not contain a critical catalytic residue (Glu or Asp) conserved in other hotdog fold thioesterases. Based on biochemical and site-directed mutagenesis studies, we proposed a catalytic mechanism in which the conserved Arg(37) plays a crucial role in the hydrolysis of the thioester bond, and that Tyr(29) and a hydrogen-bonded water network assist the decarboxylation of the beta-ketocarboxylic acid intermediate. Moreover, computational docking suggested that the substrate-binding channel binds a polyene substrate that contains a single cis double bond at the C4/C5 position, raising the possibility that the C4=C5 double bond in the enediyne moiety could be generated by the iterative polyketide synthase. Together, the results revealed a hotdog fold thioesterase distinct from the common type I and type II thioesterases associated with polyketide biosynthesis and provided interesting insight into the enediyne biosynthetic mechanism.

PubMed: 19357082
DOI: 10.1074/JBC.M809669200

実験手法

X-RAY DIFFRACTION (1.75 Å)